Isotopocule analysis of hydrocarbon contamination

Methods for identifying hydrocarbon contamination sources may include fingerprinting hydrocarbons using isotopocule analyses for BTEX compounds. For example, methods for identifying hydrocarbon contamination sources may comprise: extracting BTEX compounds from a sample; measuring the isotopocule composition of the BTEX compounds; and determining a characteristic of the sample based on the isotopocule composition. Such characteristics may include, but are not limited to, the characteristic of the sample comprises one or more selected from the group consisting of: a source of the sample, a condition at which the sample formed or was last equilibrated, a migration time from a source to a sample location, weathering of the sample, and degree to which the sample is anthropogenic and naturally-occurring.